Electrically powered devices for preparing beverages, in particular hot beverages such as tea or coffee, including such beverages that are prepared using portioned ingredients for instance contained in capsules or pods, have been developed and have become very popular, for use at home as well as out of home.
However, such devices, especially those having electric heaters for heating up the liquid of the beverage, consume a significant amount of electric energy to be maintained in a state of operative immediate readiness between two beverage preparation cycles.
Typically the user would leave the machine switched on after a beverage has been prepared, for no particular purpose or just to avoid a lengthy start-up period between consecutive beverage preparations. Such annoying start-up procedures are in particular required in case of pre-heating and/or self-cleaning of the machine.
This, however, goes against a generally sought aim, especially in more recent times, towards energy savings. Considering the wide use of beverage preparation devices, it is all the more desirable to provide such devices that waste less energy and are thus more environmentally friendly.
It has been proposed to reduce to some degree unnecessary waste of energy resulting from electric beverage preparation devices that are left switched on without being used to prepare beverages, by incorporating automatic turn-off systems and standby systems into such devices, in particular timers.
Automatic shut-down systems in beverage preparation machines are addressed in DE 199 24 279, U.S. Pat. Nos. 3,969,610. 6,752,069, 7,197,367, WO 95/34236, WO 2004/098360 and WO 2009/092745.
As mentioned above, a significant problem with the known automatic shut-down arrangements for saving energy during periods of inactivity, whether the machine is completely shut off or merely run down into a standby mode, is the time needed to start-up again the beverage preparation machine. This start-up period is needed for the reactivation of machine components, such as a sufficient preheating of the machine's thermoblock, or to run a cleaning cycle before the machine is again in a state of operative readiness to prepare beverages. Hence, a user has to wait during the entire start-up period before requesting and being served a beverage. To avoid this drawback, users tend to leave the machine permanently or for an extended period of time in its operative mode, even when not used to prepare beverages, and in which mode it consumes a significant amount of energy just to be maintained in its state of immediate operative readiness.
A partial solution to this problem has been proposed by substituting thermoblocks by on-demand heating systems, for instance as disclosed in EP 1 253 844, which can be re-activated instantly. This approach, involving heating tubes with resistive thick-films, remains however relatively expensive and inappropriate for certain machine segments.